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Pseudoxanthoma Elasticum

Thursday, 19 August 2004

Thursday, 27 January 2005

PXE, Gronblad-Strandberg syndrome

What

Pseudoxanthoma Elasticum (PXE) is a rare inherited disorder of the connective tissue. The connective tissues are the structural parts of the body that essentially hold the body’s cells together and form a framework for the body. One of the major parts of connective tissue is a protein named elastin. Elastin gives connective tissue the capability of stretching and returning to the original length like a spring. In PXE, calcium deposits into the elastic fibers of the connective tissue. These calcium deposits alter the normal function of the connective tissue. PXE results in changes in the skin, eyes and cardiovascular system.

Who

PXE can occur in children from all ethnic backgrounds, but occurs somewhat more often in the Dutch. Children with PXE can have either the autosomal recessive type, or autosomal dominant, where only one of the two gene copies is changed. If children have only one copy of the gene, the disease tends to be much more mild. It is not known exactly how often the disease occurs, but those with only one copy of the gene are included, it is probably around 1:26,000. The autosomal recessive type, where both copies are changed, is considerably more rare. Females are affected twice as often as males and the reason for this is not known. The average age that signs and symptoms first appear is 13 years, however, ages can vary between infancy and 70 years or older.

Signs and Symptoms

The range of different signs and symptoms that children can have is variable, with those with only one copy of the gene showing very mild symptoms. The disorder can affect the skin, the eyes and the cardiovascular system. Most of these problems appear later in life, and children usually do not have detectable symptoms until their teenage years.
Symptoms associated with the skin usually appear first and include a yellowing or “cobblestone” appearing areas of skin that are usually first seen on the neck and then in the groin, arms, armpits, and the back of the knees. The skin may appear soft and wrinkled, especially in these areas.
Symptoms associated with the eyes include specific changes on the retina (the back of eye) that an ophthalmologist can recognize. These include angioid streaks (gray, orange, or red wavy streaks in front of the retina), bleeding and scarring of the retina. Vision loss could occur in people as they get older (around age 40).
When problems arise in the cardiovascular system, they are often due to deposits of calcium in arteries. This can lead to symptoms of leg pain during walking (claudication), hypertension, and put people at a higher risk for heart attacks. Occasionally there may be bleeding from blood vessels in the stomach as well.

Possible Causes

PXE is caused by a change (mutation) in a gene called ABCC6 (also known as MRP6). This change can either arise spontaneously in a child, or be inherited from parents. Although the responsible gene has been identified, how this abnormal gene causes the calcium deposits on the elastic connective tissues in PXE is still unknown. Other genes may affect how severe the disease is in any particular individual.

Diagnosis

A diagnosis of PXE is suspected based on the physical signs and symptoms described above. The presence of red, raised, cobblestone-like bumps on the side of the neck is usually the first sign of PXE to appear in children. A skin biopsy (a test where a small area of skin is removed for closer examination) can provide a definitive diagnosis of PXE. Examination of the removed skin with a microscope reveals the presence of calcium in the elastic tissues.

Treatment

The mainstay of treatment for PXE is monitoring for early signs of bleeding in any critical area, such as the stomach or eyes. The patient’s regular doctor can check for signs of bleeding in the stomach or bladder.
Regular follow-up with a specialist vascular surgeon and/or cardiologist is needed for those who have cardiovascular problems. Diet and exercise, and if needed, medications can be used to help treat ancillary problems like high blood pressure or cholesterol. This may help decrease the chances of heart disease and improve symptoms of claudication.
There is currently no effective treatment for the skin lesions, but the appearance may be improved by plastic surgery.
All patients should have regular visits with the ophthalmologist. Patients can also monitor their vision regularly at home in order to detect any signs of bleeding early. Ophthalmolgists can manage bleeding in the eyes in some cases with laser surgery.

Prognosis

Children with PXE are expected to have a normal life span but with an increased chance of cardiovascular and circulatory problems, gastrointestinal bleeding and impaired vision.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

PXE International, Inc.
Great website for parents with information on PXE, support groups, and links to other sites